The “we’re a family” thing really only works for small businesses anyways, otherwise it’s complete lip service. On the surface they may mean it, but when push comes to shove, it’s the business first. Having a great boss matters, but unless they’re the final decision-maker, they will cave or be overruled.
Nothing at all wrong with wanting to hold onto your good team members, but holding onto them can’t mean holding them back, or you will lose them.
I wouldn’t actively encourage my A players to go interview every year, but I would say that everyone should know the current market for their position. I feel like once you’ve made the decision to go through formal interviews, you’re checked out of the organization a little at that point already.
In my field I get 10+ recruiters a month minimum reaching out. I probably politely decline 80% of those inquiries, trade some exploratory emails with a couple and maaaaaaaybe talk to 1 or 2. Does not hurt to have a lot of contacts and yes, practice speaking, especially about your expertise. You have to be able to sell yourself. You never know when you can leverage those new contacts for hiring or for your own job search.
Nobody looks out for you better than you, certainly not the company you work for.